Porphyrias: inborn errors in heme production

The porphyrias are commonly labeled erythropoietic, hepatic, or erythrohepatic, depending on whether the heme biosynthetic enzyme deficiency appears in the red cells, the liver, or both. Although direct enzyme replacement therapy holds much promise for ultimate amelioration, the mainstay of management still lies in recognition of the diseases and avoidance of their precipitating factors.